The present invention pertains to optical switching systems. More particularly, the present invention relates to microelectromechanical system (MEMS) optical switches.
Recent advances in the field of communications have led to the adoption of optical communications and light transmission. Light-based signals are transmitted over optical fibers in a manner that is similar to the manner in which electronic signals are transmitted over conductive lines on a semiconductor device. Recently, miniature optical switches have been developed to alter light paths between optical fibers, similar to the function that transistors perform for electronic signaling.
One form of optical switch utilizes micro-machined mirrors, or microelectromechanical system (MEMS) mirrors. Arrays of optical switches are used to rapidly reconfigure optical networks by altering one or more light paths in a system of intersecting optical fibers. Numerous other switch applications have been identified in optical communications systems. Accordingly, numerous unique optical switch arrays are presently known.
One form of optical switch comprises a three-dimensional MEMS switch that can be independently rotated about two different axes. U.S. Pat. No. 6,087,747, herein incorporated by reference, discloses one such construction for rotating a mirror in three dimensions about two sets of torsion beams using electrostatic actuators.
According to FIG. 1, a prior art three-dimensional MEMS optical switch 10 is shown having five different mechanical planes. Switch 10 comprises an array (or bundle) 12 of input fibers 16 and an array 14 of output fibers 18. Switch 10 also includes a microelectromechanical system (MEMS) input mirror 20 and a MEMS output mirror 22.
A light beam 24 is generated from input fiber 16 which is supported, or carried, by an input fiber substrate 26. Light beam 24 is then reflected by input mirror 20 onto a fixed mirror 30. Input mirror 20 is carried on an input mirror substrate 28. Reflected light beam 24 is further reflected by output mirror 22 on an output mirror substrate 32 for optical alignment with output fiber 18. Output fiber 18 is carried by an output fiber substrate 34.
Substrate 26 forms a first mechanical plane. Substrate 28 forms a second, independent mechanical plane. Fixed mirror 30 forms a third, independent mechanical plane. Substrate 32 forms a fourth, independent mechanical plane. Finally, substrate 34 forms a fifth, independent mechanical plane.
One problem associated with such prior art switch 10 results from difficulties encountered because of the five different mechanical planes. Such multiple planes cause assembly (or fabrication), alignment and mechanical drift problems. Furthermore, a typical construction for switch 10 is usually limited to N inputs and N outputs.
Accordingly, improvements are needed in the design and construction of such optical switches.
A three-dimensional MEMS optical switch provides one or more input mirrors and one or more output mirrors on a single, common substrate. Additionally, at least one input light source and at least one output light source are carried by the substrate. A fixed mirror is provided opposite the substrate. Both the input mirror and the output mirror are movable to impart alignment when transferring a light beam from an input light source to an output light source. In one case, the input mirror and the output mirror are rotatably actuatable about two perpendicular axes, as a gimbal, so as to direct an optical beam in three-dimensional space in order to project the optical beam onto a desired, selected spot on an opposing substrate in a two-dimensional plane. Preferably, the input mirrors and the output mirrors are dedicated to respective input fibers and output fibers, respectively.
According to one aspect, an optical switching system includes a substrate, a microelectromechanical system (MEMS) input mirror, a MEMS output mirror, and an opposing mirror. The substrate is configured to carry an input light source and an output light source spaced from the input light source. The microelectromechanical system (MEMS) input mirror is carried by the substrate. The MEMS output mirror is carried by the substrate and is spaced from the MEMS input mirror. The opposing mirror is disposed opposite the substrate and is configured to communicate optically with an input light source and an output light source carried by the substrate. The input mirror optically couples an input beam from the input light source via the opposing mirror to a location on the opposing mirror with the output mirror via the opposing mirror. The output mirror optically couples the location on the opposing mirror with the output light source via the opposing mirror.
According to another aspect, an optical switch includes a support structure, an input fiber, an output fiber, a stationary mirror, an input mirror, and an output mirror. The input fiber is carried by the support structure. The output fiber is carried by the support structure and is spaced from the input fiber. The stationary mirror is provided opposite the input fiber and the output fiber, and is tilted relative to respective optical paths for each of the input fiber and the output fiber. The input mirror is provided on the support structure optically aligned with an optical path reflected off the stationary mirror from the input fiber. The output mirror is angularly movable relative to the stationary mirror. The input mirror is angularly movable relative to the stationary mirror to optically align the reflected optical path from the stationary mirror so as to reflect off the stationary mirror and optically align with the output mirror. The output mirror is angularly movable relative to the stationary mirror to optically align the reflected optical path from the stationary mirror so as to reflect off the stationary mirror and optically align with the output fiber.
According to yet another aspect, an electro-optical mechanical device includes a support structure, an array of input fibers, an array of output fibers, at least one optical reflector, an array of rotatable input mirrors, and an array of rotatable output mirrors. The array of input fibers is carried by the support structure. The array of output fibers is carried by the support structure spaced from the array of input fibers. The at least one optical reflector is carried opposite the array of input fibers and the array of output fibers. The array of rotatable input mirrors is carried by the support structure. A selected input mirror is actuatable in optical alignment through the optical reflector with a selected input fiber. The array of rotatable output mirrors is carried by the support structure, wherein the selected input mirror is rotatably actuated to align an optical beam from the selected input fiber with a selected output mirror. The selected output mirror is rotatably actuated to align the optical beam with a selected output fiber.
Some embodiments of the present invention provide for a structure that can be built or assembled onto a single, common support surface in combination with an opposed mirror. Hence, an advantage is provided in that MEMS components and light inputs and light outputs can be fit onto one mechanical plane which is cheaper and easier to assemble and align than the multiple mechanical planes of the prior art technique of FIG. 1.